Structures such as bridges, parking ramps and the like are typically built to allow for thermal expansion and contraction of the structural members in accordance with daily and/or seasonal variations in temperatures Gaps are provided between adjacent structural sections to allow for such characteristics, and various materials are utilized to form joints to bridge the gaps. Such joint materials must allow for the expansion, contraction and other movement of the structural members, as well as provide protection against water penetration. They must also be durable enough to withstand wear and tear from vehicular and/or pedestrian traffic, snow removal equipment, road chemicals, and other hazards.
Various joint materials have been utilized heretofore. Some joint materials comprise a rubber or synthetic rubber seal or bellows section incorporated into a metal nosing which is secured to the adjacent structural members. Such joint materials are expensive to make and install, and are very difficult to repair if damaged. Further, the bellows section tends to collect dirt and debris when expanded, and can subsequently become crushed when the joint gap closes upon expansion of the structural members. The same problem is present with so called compression seals, which include a preformed flexible material placed in the joint gap under compression.
Another commonly used type of joint materials are known in the industry as T-joints because portions of the structural sections adjacent to the gap are cut away to provide a recessed area below the top surface which, together with the joint gap cross section, form a T-shaped outline. Such T-joint materials are commercially available from various suppliers in many sizes and configurations. T-joints are relatively inexpensive and provide a joint surface which is generally even and flush with the top surface of the structural members; however, if they are not prefabricated, they tend to be complicated or difficult to install, and have relatively poor strength and short service life.
Such T-joints typically consist of a thin center section of resilient material, which is usually bonded to the adjacent structural members with an epoxy based adhesive and which is supported by an underlying metal traffic-bearing plate. The thin resilient center section is either prefabricated or poured in place. Only relatively small areas are provided along the sides for adhesion between the center section and the structural members or the epoxy adhesive bedding compound. Stress in the joint is concentrated in these areas and the most frequent failures occur there. Incomplete or improper application of the epoxy adhesive bedding compound during installation in the field often contributes to a weakened bond between the center section and the bedding compound Because of their considerable width, such joints are susceptible to tearing by vehicle wheels while starting, stopping or turning on the joint materials, and/or by snow plows and other abrasion. Further, the relatively wide expansion joints of the prior art often tend to present a trip hazard as a result of bulging caused by compression of the resilient material due to expansion of the structural members during periods of higher temperatures. In these joints, the width is determined by the elastomeric properties of the joint materials, and the desire to reduce the cohesive and adhesive failures caused by the cyclical loads applied to the system. Thus, these joints have a width typically four to six times the expected movement in expansion and this causes the center section to be increasingly susceptible to tearing and other forces from vehicle tires, etc. resulting in adhesive and cohesive failure in the joint materials.
A need has thus arisen for an improved expansion joint system incorporating a preformed substantially continuous resilient center section which is reinforced along the edges in order to increase overall adhesive bond strength while minimizing joint width and susceptibility to damage and/or cohesive failure.